Pathogenesis of transient ischemic attacks within the vertebrobasilar arterial system

Area of Science:

• Neurology
• Vascular Neurology
• Cerebrovascular Physiology

Background:

• Vertebrobasilar arterial insufficiency (VBI) affects blood flow to the posterior circulation of the brain.
• Understanding the hemodynamic changes in VBI is crucial for diagnosing and managing the condition.

Purpose of the Study:

• To investigate regional cerebral blood flow (rCBF) changes in patients with VBI under normal and hypotensive conditions.
• To explore the role of dysautoregulation and hemodynamic factors in the pathogenesis of VBI.

Main Methods:

• Xenon 133 inhalation technique was used to measure rCBF.
• Measurements were taken in 36 VBI patients, 3 with brain stem infarction, and 15 controls.
• rCBF was assessed in supine position and after inducing postural hypotension.

Main Results:

• No significant difference in resting rCBF between VBI patients and controls.
• Postural hypotension significantly reduced rCBF in VBI patients, irrespective of papaverine treatment.
• Dysautoregulation was initially localized but became widespread in long-standing VBI.

Conclusions:

• Hemodynamic factors and dysautoregulation are implicated in the development of VBI symptoms.
• VBI patients exhibit impaired autoregulation, particularly under stress such as postural hypotension.